The oil spill in the Gulf of Mexico has many Minnesotans thinking more about the gasoline they use and where it comes from. But very little of the state's oil comes from the gulf.
Instead, Minnesota receives most of its oil from Canada, where oil sands production also carries environmental risks.
FROM ALBERTA TO ROSEMOUNT
Much of the state's gasoline is produced at the Flint Hills refinery in Rosemount, south of St. Paul. With seven crude oil tanks and about two million barrels of capacity, the maze of towers, tanks, pipes and pumps is the biggest refinery in the Midwest outside of Chicago.
It produces gasoline and other products that include propane, butane, jet fuel, diesel fuel and asphalt. Crude oil arrives at Flint Hills in a pipeline that runs more than 1,000 miles to Alberta, Canada, home to the world's second-largest proven oil reserves after Saudi Arabia.
The pipeline occasionally springs a leak, but those spills are usually small and can be cleaned up quickly.
"In Minnesota we are geographically blessed. It may not seem that way in the middle of winter, but we really are," Flint Hills spokesman Jake Reint said. "We have access to a very stable, reliable fuel supply, in Canada, where the majority of our fuel, our feedstock, comes from."
Canadian crude is heavier and contains more sulfur than oil from most other places, requiring more energy to turn it into gasoline and other products. The carbon footprint of producing Canadian oil can be up to a third higher than for conventional oil.
Most of Canada's oil doesn't come from deep wells, but from the ground itself. The oil is called bitumen -- a tarry, sticky substance mixed right in with the soil.
To get at it, oil companies strip the land of trees and wetlands then dig into the ground, hauling extracting four tons of earth for each barrel of oil. They use hot water and solvents to separate the bitumen from the soil, and pump the waste into huge ponds. The bitumen is then treated further to turn it into crude.
All this is happening in a place a lot like Minnesota's Boundary Waters Canoe Area Wilderness.
The bitumen-laced dust and toxic chemicals from the processing plants drift into the air and water. Critics say the waste ponds are seeping into groundwater, adding more toxic chemicals.
OIL PRODUCTION HARMS ABORIGINAL TRIBE
Downstream from the oil sands -- further north in Alberta at the mouth of the Athabasca River -- some members of the Athabasca Chipewyan First Nation say oils sands production is destroying their lives.
"Our elders have been saying this since the 60s and 70s, that this is bad, this is going to destroy the land, this is going to be no good for the people," said Mike Mercredi, a tribal member who records interviews with elders.
They describe deformed fish with flabby flesh, and other changes that have persuaded many of them to quit eating their traditional diet.
Tribal elders say they're suffering much higher rates of a rare bile duct cancer. They believe the fish and other wildlife they depend on have been contaminated by the oil projects.
Mercredi said researchers from the University of Alberta and elsewhere have tracked high levels of cancer-causing chemicals, mercury and bitumen. He said oil producers' flue gas stacks emit the chemicals, which land on snow.
"The snow melts and all the runoff gets into the rivers," Mercredi said. "From what they have found, it's equivalent to oil spill every year. So can you imagine the people consuming that for 30 years."
A study by the provincial government found higher than expected numbers of blood, lymphatic and biliary tract cancers among the First Nation people. But it did not blame pollution for the increase.
ENVIRONMENTAL DISASTER POSSIBLE, BUT UNLIKELY
Preston McEachern, an administrator for the provincial agency responsible for protecting Alberta's environment, said his studies have not documented increases in toxic chemicals down river from the oil sands mines.
But officials are keeping a close eye on the mines, said McEachern, section head for science research and innovation in oil sands and clean energy for Alberta Environment
"Do we have concerns for something catastrophic in the oil sands?," McEachern said. "Yes."
McEachern said it would be an environmental disaster if the earthen walls holding in an oil sand producer's waste pond were to fail. But he said that is unlikely.
"It's not like deep-sea drilling," he said. "There's decades in this business of managing structures, and doing so in a very, very safe way."
McEachern said he is more concerned about ensuring that companies reclaim the waste ponds. So far only 10 percent of the disturbed land has been replanted, he said.
Critics say those reclaimed acres have sustained nowhere near the diversity and richness of the natural landscape. But McEachern said new ways of handling the waste will enable companies to reclaim the ponds faster.
CRITICS: "THEY'RE GOING TO MORE AND MORE RISKY PLACES"
For critics, the damage to the land and pollution created by oil sands production raises a disturbing question: Why do the companies need to go to such lengths to remove oil from the ground?
Simon Dyer, oil sands program director of the Pembina Institute, a Calgary, Alberta think-tank, said deep offshore drilling and oil sands development are two symptoms of the same problem.
"We're running out of oil so they're going to more and more risky places and places where the environmental impacts are higher and higher in order to maintain our access to oil," Dyer said.
Demand for the oil is growing. Canada is debating a proposal to build a pipeline from Alberta to the west coast, where crude can be loaded onto Chinese tankers.
Most of the bitumen in Alberta is too deep to mine from the surface. Companies are starting to use a new form of drilling that involves other kinds of environmental risks.
That process injects steam into the ground to soften the bitumen and force it out. But it uses even more energy than mining for bitumen, and the network of roads, pipelines and other infrastructure puts caribou and elk at risk.